Bobbin case



Feb. 2, 1943 D. GARDNER BOBBIN CASE Filed May 28, 1940 INVENTOR DWIGHT R. GARDNER Patented Feb. 2, 1943 UNETED STATES FATENT OFFICE BOBBIN CASE Application May 28, 1940, Serial No. 337,599

Claims. (01. 112-233) The present invention relates to thread cases or bobbin cases for the shuttles of sewing machines.

The principal object of the invention is to provide novel and improved means in a bobbin case to control thread delivery and prevent spilling or overrunning of the thread.

In the accompanying drawing,

Figure 1 is a plan view of a bobbin case embodying the features of this invention in its preferred form;

Fig. 2 is a sectional view, taken on the line 22 of. Fig. 1, of the bobbin case shown mountedv in a conventional form of sewing machine shuttle;

Fig. 3 is a detail view in perspective of one form of the thread conrtolling device removed. from the bobbin case;

Fig. 4 is a sectional elevation of a bobbin case of a modified form; and

Fig. 5 is a sectional View, taken on the line 5-5 of Fig. 4.

The bobbin case 2 and the rotary shuttle 4 illustrated in the drawing may be of conventional form.

The bobbinv case is provided with the usual cylindrical wall 6, outer end wall 8 and tubular post or arbor I0 which is adapted to be received on a post I2 of the shuttle. the post I2 is provided with an annular groove I4 which is adapted to receive a slidable latch on the end wall 8 of the bobbin case to hold the bobbin case in position on the post, the latch I6 being adapted to be released from the post by means of the usual latch lever l8 pivoted on the end wall of the bobbin case. The cylindrical wall of the bobbin case may be provided with the usual thread-guiding aperture and thread tension spring 22 beneath which the thread 24 passes.

The thread may be supplied to the bobbin case in the form of a ready wound bobbin having a paper core 26 on which the. thread is wound. The thread bobbin is mounted in the bobbin case by placing it on the post or arbor 10 of the bobbin case, the core being slipped over the arbor.

In accordance with the present invention, a device is mounted in the bobbin case for the pur pose of preventing spilling or overrunning of the thread as it leaves the bobbin. This device comprises an annular disk 28 from the periphery of which there is a projection in the form of a spring 30 which is arranged in more or less convolute form as shown. The disk portion 28 may The end of be provided with a slot 32 and one or more depending lugs 34.

This device is inserted in the bobbin case by positioning the disk 28 against the inner side of the end wall of the case. The slot 32 permits the disk 28 to be circumferential'lycontracted so that when released it firmly engages the inner side of the cylindrical wall of the case. The lugs 34 may be received in an aperture in the end wall of the case to assist in holding the disk in position.

When thedevice isth-us placed in the case, the spring 30 extends a distance about the post or arbor l0 and the edge 36 of the spring projects a distance beyond the end of the arbor It With this construction, to insert the bobbin in the bobbin case the bobbin is tipped slightly and pressed against the end portion of the spring 30 so as to force said end outwardly a sufficient distance to permit the bobbin to be slipped over the arbor Ill, the bobbin being given a partial turn as it is applied so as to permit it to be easily slipped between the arbor and the end portion of the spring. When the bobbin has thus been applied to the bobbin case and the thread inserted through the thread guide 20 and beneath thetension spring 22, the outer portion of the spring 30 bears on the peripheral surface of the thread mass of the bobbin. With the bobbin thus applied, the thread case may be inserted in the shuttle ready for operation.

With this construction, the end portion of the spring 30 resiliently bears on the peripheral surface of the thread mass so as to cause the bobbin, as the thread is drawn therefrom, to rotate against the arbor I0, and thus cause the stretch of thread extending from the thread mass to the tension spring 22 to be maintained uniformly taut during the unwinding of the bobbin. This pressure over a substantial portion of the width of the thread mass effectively insures against overrunning or spilling of the thread as the bobbin is unwound. The pressure exerted on the periphery of the thread by the spring 30 diminishes as the thread mass decreases in diameter, which insures uniform resistance to overrunning of the bobbin during the entire unwinding operation, less resistance to overrunning being required as the thread mass decreases in diameter.

The device takes up a minimum amount of space in the bobbin case and does not materially lessen the amount of thread that may be used in the case.

The device may be either furnished with the bobbin cases, or may be supplied separately and easily applied by the sewing machine operator to existing bobbin cases.

The form of device illustrated in Fig. 4 consists essentially of a spring 38 which has one end extending through the usual slot 40 in the cylindrical wall of the case in which the fixed end of the tension spring 22 extends, and is secured to the case by means of the usual screw 42 which also secures the tension spring 22 to the case.

The portion of the spring 38 that is arranged inside of the case is in more or less convolute form and its free end portion engages the periphery of the thread mass similarly to the spring 30. It may be noted that this form of device also may be easily and quickly applied to existing bobbin cases.

As will be evident to those skilled in the art, my invention permits various modifications without departing from the spirit thereof or the scope of the appended claims.

What I claim is:

1. In a bobbin case of the class described having a cylindrical wall, an end wall and a bobbin receiving post, a member of spring material having a resilient base portion positioned adjacent the inner side of said end wall, said base portion being slotted so as to permit it to be contracted circumferentially when inserted in the case to cause it to yieldingly engage the inner side of the cylindrical wall to hold said member in place, and a portion in the form of a spring projecting from the periphery of said base portion and convolutively arranged about said bobbin post whereby when a bobbin is in position on the post the outer free end portion of the spring bears under compression on the periphery of the bobbin, the pressure decreasing as the bobbin unwinds.

2. A device of the class described adapted to be used in a bobbin case having a cylindrical wall, an end wall, and a bobbin receiving post, comprising a member of springmaterial having a resilient base portion adapted to be positioned against the inner side of the end wall of the bobbin case, said portion being provided with means to permit it to be-contracted circumferentially when inserted in the case to cause it to yieldingly engage the inner side of the cylindrical wall of the case to hold said member in place, and a portion in the form of a spring projecting from the periphery of said base portion and convolutively arranged about the bobbin post when said member is inserted in the bobbin case whereby when the device is positioned in the bobbin case and a bobbin is positioned on the post, the outer free end portion of the spring bears under pressure on the periphery of the bobbin.

3. In a bobbin case of the class described having a cylindrical wall, an end wall and a bobbin receiving post, a member having a base portion provided with means for securing it adjacentthe inner side of said end wall, and a portion in the form of a spring projecting from the periphery of said base portion and convolutively arranged about said bobbin post, whereby, when a bobbin is in position on the post, the outer free end portion of the spring bears under pressure on the periphery of the bobbin, the pressure decreasing as the bobbin unwinds.

4. An attachment for a bobbin case of the class described having an end wall and a bobbin receiving post, comprising a member of spring sheet material having a base portion provided with means for securing it against the inner side of said end wall, and a portion in the form of a spring projecting inwardly from the periphery of said base portion and convolutively arranged about said bobbin post when said member is inserted in the bobbin case, whereby when a bobbin is in position on the post the outer free end portion of the spring bears under pressure on I the periphery of the bobbin, the pressure decreasing as the bobbin unwinds.

5. In a bobbin case of the class described having a cylindrical wall, an end wall and a bobbin receiving post or arbor projecting centrally from said end wall, the improvement which comprises a single piece member of spring sheet metal having one end secured to the bobbin case and the remaining portion thereof extending convolutely from a point adjacent the inner side of said 05'- lindrical wall of the bobbin case and about said bobbin receiving arbor, the outer edge of the free end portion of said spring member projecting a distance outwardly beyond the outer end of said arbor, whereby, to insert a bobbin in the case, its peripheral surface may be pressed against the projecting edge of the free end of the spring member so as to force said end away from the arbor a sufilcient distance to allow the bobbin to be slipped over said arbor with said free spring end bearing on the peripheral surface of the bobbin.

DWIGHT R. GARDNER. 

